DE102016108734B4 - Coated body and method of making the body - Google Patents

Abstract

A coated body having a substrate and a wear resistant coating applied to the substrate by physical vapor deposition, the coating comprising:
a base layer applied to the substrate to a thickness of 1 to 10 µm, the base layer being formed from a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof; and
a cover layer adjoining the base layer with a thickness of 0.1 to 5 µm, the cover layer comprising repeating alternating layers of an oxynitride layer and a nitride layer arranged over the oxynitride layer,
wherein the oxynitride layer is an oxynitride of aluminum and optionally other metals from the group consisting of chromium, hafnium, zirconium, yttrium, silicon and combinations thereof and the nitride layer is a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si , Zr and combinations thereof is formed,
wherein in the repeating alternating layers between the oxynitride layer and the nitride layer and optionally between successive alternating layers there is an intermediate layer formed from an oxynitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof is and
wherein the oxynitride layer has a nitrogen content of less than 50 atomic percent based on the content of nitrogen and oxygen in the oxynitride layer.

Description

The present invention relates to a coated body, in particular a cutting tool, with a substrate and a wear-resistant coating on the substrate, and a method for its production.

The cutting tools used for machining metals and metal alloys such as steel and cast iron usually consist of a base body and a coating applied to the base body, which can include one or more layers of hard materials such as titanium nitride, titanium carbide, titanium carbonitride, titanium aluminum nitride and/or aluminum oxide. The coating serves to make the cutting insert harder and/or more wear-resistant and to improve the cutting properties. Both CVD processes (Chemical Vapor Deposition) and PVD processes (Physical Vapor Deposition) are used to apply the coating.

In particular, arc evaporation (arc-PVD) and cathode sputtering (sputtering) are known as PVD processes. In sputtering, atoms from a cathode metal (target) are bombarded by energetic ions from a plasma and then deposited onto a substrate placed near the target. In the presence of a reactive gas, reaction products of the target atoms and the reactive gas form on the substrate. An inert gas such as argon is usually used as the working gas to generate the plasma.

The PVD processes are commonly used to deposit titanium nitride and titanium aluminum nitride. The addition of aluminum increases the hardness and oxidation resistance of the titanium nitride layers. Also known is the use of titanium-free layers such as AlCrN, which can be doped with other chemical elements such as silicon to improve the layer properties.

PVD processes for the deposition of hard aluminum oxide layers use voltage-pulsed cathodes in order to avoid poisoning of the metal targets by the electrically non-conductive aluminum oxide. To produce the aluminum oxide layer, two magnetron sputtering sources with aluminum targets can be connected to a sine wave generator in such a way that the two sputtering sources act alternately as the anode and cathode of the sputtering arrangement with a pulse frequency of between 20 and 100 kHz.

The US 8,709,583 B2 discloses a cutting tool having a body and a multi-layer coating applied thereto, which has a first layer of TiAlN with a layer thickness of 1 to 5 µm and a second layer of aluminum oxide with a layer thickness of 1 to 4 µm, the coating further on the second Layer of aluminum oxide also comprises n layers of TiAlN and layers of aluminum oxide applied alternately one on top of the other, each with a layer thickness of 0.1 to 0.5 μm, where n refers to each individual layer and is an even number from 0 to 10 and where the Total layer thickness of the coating is 2 to 16 microns and the coating is produced using the PVD process.

From the U.S. 2014/193637 A1 a cutting tool with a substrate made of hard metal, cermet, steel or high-speed steel (HSS) and a multi-layer coating deposited thereon using the PVD process is known, which has a base layer of one or more identical or different layers of a nitride or carbonitride arranged one on top of the other and a chromium-containing , Oxidic functional layer includes. The nitride or carbonitride of the base layer contains at least aluminum (Al) and optionally one or more other metals selected from Ti, Cr, Si, Y, Ru and Mo.

In order to improve the connection of the chromium-containing functional layer, according to the U.S. 2014/193637 A1 an intermediate layer is provided between the base layer and the functional layer, which consists of one or more oxides or oxynitrides of the metals Al, Cr, Si and/or Zr, the intermediate layer having a cubic structure. The chromium-containing functional layer is selected from chromium oxide (Cr ₂ O ₃ ), chromium oxynitride, aluminum chromium oxide (AlCr) ₂ O ₃ , aluminum chromium oxynitride or a mixed oxide or mixed oxynitride made from aluminum, chromium and other metals from the group Hf, Y, Zr and Ru, and has a rhombohedral structure.

The DE 10 2010 052 687 A1 discloses a multi-layer, oxynitride coating system with cubic AIN and AION on substrates such as preferably HSS and hard metal. The layer system consists of a first adhesive layer, preferably made of the elements Cr, Al and N, with a layer thickness between 0.1 and 0.5 microns; a second support layer, preferably made of the elements Cr, Al and N, with a layer thickness between 0.3 and 2.5 microns; an oxygen-containing intermediate layer, preferably made of the elements Cr, Al, O and N, with a layer thickness between 0.3 and 2.5 microns. and an oxygen-containing oxynitride layer, preferably composed of the elements Cr, Al, O and N, with a layer thickness between 0.3 and 2.5 microns. In a second embodiment, a further cover layer made of hard material such as TiAIN is provided.

From the DE 10 2013 005 437 A1 a cutting tool with a coating of metal oxide nitride hard material layers is also known. The metallic elements of the metal oxynitride hard material layers are deposited by physical vapor deposition from at least one target, the target comprising, and preferably also, at least one metal from the group Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Al at least one element from the group Y, Ni, B and Si, the target being used for the deposition of at least three layers in different processes but using the same process parameters, with the exception of the composition of the reactive gas. The first reference layer is a metal nitride layer Me _p1 O _n1 N _m1 with n1=0, which is deposited using nitrogen as the reactive gas. The third reference layer is a metal oxynitride layer Me _p3 O _n3 N _m3 with an oxygen concentration n3 in atomic percent of at most 30%, preferably between 20 and 30%. The second reference layer is a metal oxynitride layer Me _p2 O _n2 N _m2 with an oxygen concentration n2 in atomic percent greater than n1 and less than n3 and preferably in a range between 5 and 20%, the second reference layer and the third reference layer using be separated from nitrogen and oxygen as reactive gas. For the reference slices it also applies that p1 = p3 = p2 and p1/(m1 + n1) = p3/(m3 + n3) = p2/(m2 + n2). The reference layers should not contain any oxide phases.

The CN 102 206 808 A describes a multi-layer coating that is made up of a plurality of alternatingly applied AION and TiAIN layers. A metal, a carbide, a ceramic or a plastic can be used as the substrate.

The DE 10 2008 013 965 A1 relates to a hard material-coated body with multiple layers applied by CVD, in which on a Ti _1-x Al _x N layer, a Ti _1-x Al _x C layer and / or a Ti _1-x Al _x CN layer an Al ₂ O ₃ layer is arranged as the outer layer.

The EP 1 354 984 A2 discloses a wear protection layer on cutting tools, essentially consisting of nitrides with the metal components Cr, Ti and Al and preferably a small proportion of elements for grain refinement, characterized by a Cr content of 30 to 65%, an Al content of 15 to 35% %, and a Ti content of 16 to 40%, each based on all metal atoms in the entire layer.

The EP 0 408 535 A1 discloses a multi-coated cemented carbide body having a substrate containing at least one metal carbide, a metal binder, and a multi-layer coating. The cemented carbide body comprises a bonding layer of carbide, nitride, carboxynitride, carboxide and/or carbonitride of one or more of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Si and/or B between the substrate and a α-aluminum oxide layer, and a kappa modification layer of (Al _x Ti _y )(O _w C ₂ ) between this α-aluminum oxide layer and an overlying kappa aluminum oxide layer, where y : x = 2 - 4 and z : w = 0, 6 - 0.8.

The object of the present invention is to provide further coatings for cutting tools with improved performance and increased service life for the machining of various metals and metal alloys.

The object of is achieved according to the invention by a coated body according to claim 1, a coated body according to claim 13, a method according to claim 14 and a method according to claim 26.

• eine auf das Substrat aufgebrachte Grundschicht in einer Dicke von 1 bis 10 µm, bevorzugt 1 bis 5 µm, wobei die Grundschicht aus einem Nitrid von Aluminium und wenigstens einem weiteren Metall aus der aus Ti, Cr, Si, Zr und Kombinationen davon bestehenden Gruppe gebildet ist; und
• eine an die Grundschicht angrenzende Deckschicht in einer Dicke von 0,1 bis 5 µm, bevorzugt 0,1 bis 3 µm, wobei die Deckschicht sich wiederholende Wechselschichten aus einer Oxinitridlage und einer über der Oxinitridlage angeordneten Nitridlage umfasst, wobei die Oxinitridlage aus einem Oxinitrid von Aluminium und wahlweise weiteren Metallen aus der aus Chrom, Hafnium, Zirkonium, Yttrium, Silizium und Kombinationen davon bestehenden Gruppe und die Nitridlage aus einem Nitrid von Aluminium und wenigstens einem weiteren Metall aus der aus Ti, Cr, Si, Zr und Kombinationen davon bestehenden Gruppe gebildet ist;
• wobei in den sich wiederholenden Wechselschichten zwischen der Oxinitridlage und der Nitridlage und wahlweise zwischen aufeinanderfolgenden Wechselschichten jeweils eine Zwischenlage vorgesehen ist, die aus einem Oxinitrid von Aluminium und wenigstens einem weiteren Metall aus der aus Ti, Cr, Si, Zr und Kombinationen davon bestehenden Gruppe gebildet ist und
• wobei die Oxinitridlage einen Sticktoffanteil von weniger als 50 Atomprozent, bezogen auf den Anteil von Stickstoff und Sauerstoff in der Oxinitridlage, aufweist.

This object is achieved according to the invention by a coated body with a substrate and a wear-resistant coating applied to the substrate by physical vapor deposition, the coating comprising the following:

• a base layer applied to the substrate in a thickness of 1 to 10 µm, preferably 1 to 5 µm, the base layer being formed from a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof is; and
• a top layer adjoining the base layer with a thickness of 0.1 to 5 μm, preferably 0.1 to 3 μm, the top layer comprising repeating alternating layers of an oxynitride layer and a nitride layer arranged over the oxynitride layer, the oxynitride layer consisting of an oxynitride of aluminum and optionally other metals from the group consisting of chromium, hafnium, zirconium, yttrium, silicon and combinations thereof; and the nitride layer is a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof is formed;
• wherein in the repeating alternating layers between the oxynitride layer and the nitride layer and optionally between successive alternating layers there is an intermediate layer formed from an oxynitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof is and
• wherein the oxynitride layer has a nitrogen content of less than 50 atomic percent based on the content of nitrogen and oxygen in the oxynitride layer.

By incorporating nitrogen and optionally other metals such as Cr, Hf, Zr, Y and/or Si in the crystal lattice of aluminum oxide to form an oxynitride layer, it is surprisingly possible to increase the service life of cutting tools with substrates coated according to the invention during wet and/or dry milling of materials such as steel, in particular stainless steel (SS) or high-speed steel (HSS), and/or cast iron compared to cutting tools with known coatings. The provision of at least one alternating layer of oxynitride layer and nitride layer means that the cover layer can be made thinner overall without leading to a reduction in the service life of the coated cutting tool.

The inventors have recognized that the layers modified by the incorporation of nitrogen in the crystal lattice of aluminum oxide have greater hardness than pure oxide layers. At the same time, wear resistance at high temperatures is improved. In comparison to the nitride layers optionally doped with oxygen, the oxidation resistance of the coating according to the invention is improved and at least comparable hardness and wear resistance are achieved.

Substrates suitable for producing the coated body according to the invention are known. For example, the substrate can be made of a cemented carbide, cermet, cubic boron nitride (pcBN), steel, or high-speed steel.

In a preferred embodiment, the base layer of the coating consists of aluminum titanium nitride (AlTiN) and/or aluminum titanium silicon nitride (AITiSiN), particularly preferably aluminum titanium nitride. Aluminum titanium nitride (AlTiN) is well suited as a base layer because it is very tough and hard and has excellent wear properties, especially at the high temperatures that occur during metal cutting.

In the case of the wear-resistant coated body according to the invention, the base layer typically has an Al:Ti atomic ratio of from 60:40 to 70:30, preferably from 62:38 to 68:32. For all ranges, the specified end values are included.

The top layer adjacent to the base layer in the coating can have from 2 to 10 repetitions, preferably 3 to 5 repetitions, of the at least one alternating layer of oxynitride layer and nitride layer. The thickness of an alternating layer of oxynitride layer and nitride layer is preferably in a range from about 0.1 μm to 1 μm. The oxynitride layer and the nitride layer can each have a thickness in the range of 0.05 to 0.95 μm.

The oxynitride layer in the at least one alternating layer is preferably formed from an oxynitride of aluminum, in particular AlO _x N _1-x , or an oxynitride of aluminum and chromium, in particular (Al,Cr)O _x N _1-x , particularly preferably aluminum oxynitride , where in each case 0.5 < x ≤ 0.99. The proportion of chromium in the oxynitride of aluminum and chromium can be higher, equal to or lower than the proportion of aluminum. Preferably, the oxynitride of aluminum and chromium is an oxynitride derived from aluminum oxide Al ₂ O ₃ and doped with chromium.

The oxynitride layer particularly preferably contains 1 to 30 atom % nitrogen, preferably 2 to 15 atom %. The nitrogen content in the oxynitride layer increases the bonding to the nitride layer and/or the base layer and thus improves the wear resistance of the coating.

Furthermore, according to the invention, an intermediate layer is provided in the at least one alternating layer between the oxynitride layer and the nitride layer and optionally between successive alternating layers, which consists of an oxynitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof is formed, preferably from an oxynitride of aluminum and titanium, in particular (Al,Ti)O _x N _1-x with 0<x<1, where x and/or the Al/Ti ratio can vary over the thickness of the intermediate layer. The intermediate layer preferably has an oxygen gradient, with the proportion of oxygen in the intermediate layer increasing in the direction of the oxynitride layer and/or decreasing in the direction of the nitride layer.

By arranging the intermediate layer between the oxynitride layer and the nitride layer above it in an alternating layer on the one hand and between the outer nitride layer of an alternating layer and the oxynitride layer of a further alternating layer following the alternating layer on the other hand, an even better connection of the oxynitride layers and nitride layers to one another can be achieved. This can further improve the wear resistance of the coating.

Furthermore, the intermediate layer can also be provided between the base layer and the at least one alternating layer adjoining it. The intermediate layer is then applied directly to the base layer, and the at least one alternating layer lies directly on the intermediate layer. Also in this case the intermediate layer is formed from an oxynitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof, preferably from an oxynitride of aluminum and titanium, in particular (Al,Ti)O _x N _1-x with 0 < x < 1. The spacer on the base layer may have an increasing oxygen gradient towards the oxynitride layer and/or a variable ratio of Al/Ti over the thickness of the spacer.

The intermediate layers preferably have a thickness in the range of less than 1 μm, preferably less than 0.5 μm and particularly preferably less than 0.2 μm. Particularly good results were achieved, for example, with a layer thickness of the intermediate layers in the range from 5 to 100 nm.

Finally, for decorative purposes and/or as a usage indicator, the coating can have an outermost layer of TiN, ZrN, CrN or AlCrN or mixtures of these compounds, which appear gold to silver in colour. The outermost layer makes it possible to recognize the use of a cutting edge of a cutting tool provided with the outermost layer with the naked eye.

• eine auf das Substrat aufgebrachte Grundschicht in einer Dicke von 1 bis 10 µm, wobei die Grundschicht aus einem Nitrid von Aluminium und wenigstens einem weiteren Metall aus der aus Ti, Cr, Si, Zr und Kombinationen davon bestehenden Gruppe gebildet ist; und
• eine an die Grundschicht angrenzende Deckschicht in einer Dicke von 0,1 bis 5 µm, wobei die Deckschicht mindestens eine Wechselschicht aus einer Oxinitridlage und einer über der Oxinitridlage angeordneten Nitridlage umfasst,
• wobei die Oxinitridlage aus einem Oxinitrid von Aluminium und wahlweise weiteren Metallen aus der aus Chrom, Hafnium, Zirkonium, Yttrium, Silizium und Kombinationen davon bestehenden Gruppe und die Nitridlage aus einem Nitrid von Aluminium und wenigstens einem weiteren Metall aus der aus Ti, Cr, Si, Zr und Kombinationen davon bestehenden Gruppe gebildet ist,
• wobei die Oxinitridlage einen Sticktoffanteil von weniger als 50 Atomprozent, bezogen auf den Anteil von Stickstoff und Sauerstoff in der Oxinitridlage, aufweist,
• wobei sowohl zwischen der Grundschicht und der daran angrenzenden mindestens einen Wechselschicht als auch in der mindestens einen Wechselschicht zwischen der Oxinitridlage und der Nitridlage und wahlweise zwischen aufeinanderfolgenden Wechselschichten jeweils eine Zwischenlage vorgesehen ist, die aus einem Oxinitrid von Aluminium und wenigstens einem weiteren Metall aus der aus Ti, Cr, Si, Zr und Kombinationen davon bestehenden Gruppe gebildet ist.

Furthermore, the object is achieved according to the invention by a coated body with a substrate and a wear-resistant coating applied to the substrate by physical vapor deposition, the coating comprising the following:

• a base layer applied to the substrate to a thickness of 1 to 10 µm, the base layer being formed from a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof; and
• a cover layer adjoining the base layer with a thickness of 0.1 to 5 µm, the cover layer comprising at least one alternating layer made of an oxynitride layer and a nitride layer arranged over the oxynitride layer,
• wherein the oxynitride layer is an oxynitride of aluminum and optionally other metals from the group consisting of chromium, hafnium, zirconium, yttrium, silicon and combinations thereof and the nitride layer is a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si , Zr and combinations thereof is formed,
• wherein the oxynitride layer has a nitrogen content of less than 50 atomic percent, based on the proportion of nitrogen and oxygen in the oxynitride layer,
• an intermediate layer consisting of an oxynitride of aluminum and at least one other metal from the Ti, Cr, Si, Zr and combinations thereof existing group is formed.

In a process for producing the wear-resistant coated body according to the invention, a coating with a base layer with a thickness of 1 to 10 μm is applied to a substrate, for example made of a hard metal, cermet, pcBN, steel or high-speed steel, by physical vapor deposition. preferably 1 to 5 μm, and particularly preferably from 3 to 4.5 μm, and a top layer with a thickness of 0.1 to 5 μm, preferably 0.1 to 3 μm.

The base layer and the top layer, including the at least two alternating layers of oxynitride layer and nitride layer and optionally the intermediate layers, can essentially be deposited using any suitable PVD method. However, preference is given to magnetron sputtering, reactive magnetron sputtering, dual magnetron sputtering, high power impulse magnetron sputtering (HIPIMS) or the simultaneous use of cathode sputtering (sputter deposition) and arc evaporation (arc-PVD). All layers of the coating are particularly preferably deposited by arc evaporation (arc-PVD), since particularly hard and at the same time dense layers can be deposited with this method. The inventors have also found that the droplets generated as a result of the process by means of arc-PVD can be well post-treated and that this method therefore provides a stable and flexible production method for depositing the coating according to the invention.

It is decisive for the present invention that nitrogen is continuously supplied during the PVD process for applying the coating to the substrate in the process for producing the wear-resistant coated body according to the invention, but is regulated accordingly depending on the desired composition of the respective layers of the coating.

• Bereitstellen eines Substrats;
• Aufbringen einer Grundschicht auf das Substrat in einer Dicke von 1 bis 10 µm, bevorzugt 1 bis 5 µm, wobei die Grundschicht durch physikalisches Aufdampfen aus einem Nitrid von Aluminium und wenigstens einem weiteren Metall aus der aus Ti, Cr, Si, Zr und Kombinationen davon bestehenden Gruppe gebildet wird;
• Aufbringen mindestens einer Oxinitridlage über der Grundschicht, wobei die Oxinitridlage durch physikalisches Aufdampfen aus einem Oxinitrid von Aluminium und wahlweise weiteren Metallen aus der aus Chrom, Hafnium, Zirkonium, Yttrium, Silizium und Kombinationen davon bestehenden Gruppe gebildet wird;
• Aufbringen einer Nitridlage über der Oxinitridlage, wobei die Nitridlage durch physikalisches Aufdampfen aus einem Nitrid von Aluminium und wenigstens einem weiteren Metall aus der aus Ti, Cr, Si, Zr und Kombinationen davon bestehenden Gruppe gebildet wird, und
• wahlweise Wiederholen der Schritte des Aufbringens der Oxinitridlage und der Nitridlage;
• dadurch gekennzeichnet, dass Stickstoff während des Aufdampfens der Grundschicht, der Oxinitridlage und der Nitridlage kontinuierlich und geregelt zugeführt wird.

The subject matter of the invention is therefore also a method for producing a wear-resistant coated body, which comprises the following steps:

• providing a substrate;
• Applying a base layer to the substrate to a thickness of 1 to 10 µm, preferably 1 to 5 µm, the base layer being formed by physical vapor deposition of a nitride of aluminum and at least one other metal selected from Ti, Cr, Si, Zr and combinations thereof existing group is formed;
• depositing at least one oxynitride layer over the base layer, the oxynitride layer being formed by physical vapor deposition of an oxynitride of aluminum and optionally other metals from the group consisting of chromium, hafnium, zirconium, yttrium, silicon and combinations thereof;
• depositing a nitride layer over the oxynitride layer, the nitride layer being formed by physical vapor deposition of a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof, and
• optionally repeating the steps of depositing the oxynitride layer and the nitride layer;
• characterized in that nitrogen is supplied continuously and in a controlled manner during the evaporation of the base layer, the oxynitride layer and the nitride layer.

The N ₂ partial pressure during the application of the base layer and/or a nitride layer in the at least one alternating layer of the cover layer is preferably in a range from 1 to 8 Pa, preferably 2 to 5 Pa and more preferably 3 to 4 Pa.

In particular, a mixed Al/Ti cathode, optionally doped with Cr, Si and/or Zr, can be used as the cathode. The atomic ratio of the Al/Ti cathode is preferably in the range of 60:40 to 70:30. The cathode current in this process step is preferably in a range from 150 to 250 A, more preferably in a range from 180 to 220 A.

In the oxynitride layer vapor deposition step, oxygen is supplied at a rate of 10 to 100 standard cubic centimeters/minute (sccm), preferably at a rate of 40 to 60 sccm. According to the invention, nitrogen is also supplied while maintaining a nitrogen partial pressure in the range from 1 to 8 Pa, preferably 2 to 5 Pa and more preferably 3 to 4 Pa. In particular, the nitrogen partial pressure during the evaporation of the oxynitride layer can be regulated lower than during the evaporation of the base layer or a nitride layer of the alternating layer. More preferably, the nitrogen partial pressure during deposition of the oxynitride layer is about 70 to 90% of the partial pressure during deposition of the nitride layer.

In particular, an aluminum cathode, optionally doped with chromium, hafnium, zirconium, yttrium and/or silicon, and in particular a mixed cathode, can be used as the cathode for vapor-depositing the oxynitride layer Al/Cr cathode can be used. The cathode current during the application of the oxynitride layer is preferably in a range from 100 to 140 A.

The amount of oxygen supplied is preferably kept constant during the vapor deposition of an oxynitride layer.

To form the intermediate layers before and/or after the application of an oxynitride layer, the oxygen can be supplied in the form of a rising or falling ramp with an increasing or decreasing volume flow. In particular, the oxygen supply can take place after deposition of a nitride layer in the direction of the following oxide layer with a stepwise or steadily increasing volume flow and after deposition of an oxynitride layer in the direction of the following nitride layer with stepwise or steadily decreasing volume flow.

The volume flow of oxygen supplied during the formation of the intermediate layer preferably varies in a range from approximately 50% to 100% of the volume flow supplied during the application of the oxynitride layer. During the transition from the base layer or a nitride layer to an oxynitride layer, the oxygen volume flow is preferably regulated in the form of an increasing ramp. During the transition from an oxynitride layer to an adjacent nitride layer, the volume flow of the oxygen is preferably controlled in the form of a falling ramp.

The nitrogen partial pressure is preferably kept in a range of 1 to 8 Pa, preferably 2 to 5 Pa during the formation of the intermediate layer. In particular, the nitrogen partial pressure is controlled lower during the deposition of an intermediate layer than during the deposition of a nitride layer. More preferably, the nitrogen partial pressure during the application of the intermediate layer is about 70 to 90% of the partial pressure during the application of the nitride layer.

To apply the intermediate layer, the cathode used for applying the base layer and the nitride layer is preferably used together with a further aluminum cathode. Preferably, the cathodic current at the aluminum cathode is in the range of 100 to 140 amps during interlayer deposition, and the cathodic current at the Al/Ti cathode is in the range of 120 to 180 amps, and preferably between about 120 and 160 amps.

• Bereitstellen eines Substrats;
• Aufbringen einer Grundschicht auf das Substrat in einer Dicke von 1 bis 10 µm, wobei die Grundschicht durch physikalisches Aufdampfen aus einem Nitrid von Aluminium und wenigstens einem weiteren Metall aus der aus Ti, Cr, Si, Zr und Kombinationen davon bestehenden Gruppe gebildet wird;
• Aufbringen mindestens einer Oxinitridlage über der Grundschicht, wobei die Oxinitridlage durch physikalisches Aufdampfen aus einem Oxinitrid von Aluminium und wahlweise weiteren Metallen aus der aus Chrom, Hafnium, Zirkonium, Yttrium, Silizium und Kombinationen davon bestehenden Gruppe gebildet wird;
• Aufbringen einer Nitridlage über der Oxinitridlage unter Bildung einer Wechselschicht, wobei die Nitridlage durch physikalisches Aufdampfen aus einem Nitrid von Aluminium und wenigstens einem weiteren Metall aus der aus Ti, Cr, Si, Zr und Kombinationen davon bestehenden Gruppe gebildet wird, und
• wahlweise Wiederholen der Schritte des Aufbringens der Oxinitridlage und der Nitridlage;
• dadurch gekennzeichnet, dass Stickstoff während des Aufdampfens der Grundschicht, der Oxinitridlage und der Nitridlage kontinuierlich und geregelt zugeführt wird, und
• wobei sowohl zwischen der Grundschicht und der daran angrenzenden mindestens einen Wechselschicht als auch nach dem Aufbringen der Oxinitridlage und wahlweise nach dem Aufbringen der Nitridlage jeweils eine Zwischenlage durch physikalisches Aufdampfen aufgebracht wird, wobei die Zwischenlage aus einem Oxinitrid von Aluminium und wenigstens einem weiteren Metall aus der aus Ti, Cr, Si, Zr und Kombinationen davon bestehenden Gruppe gebildet wird.

The subject matter of the invention is also a method for producing a wear-resistant coated body, which comprises the following steps:

• providing a substrate;
• applying a base layer to the substrate to a thickness of 1 to 10 µm, the base layer being formed by physical vapor deposition of a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof;
• depositing at least one oxynitride layer over the base layer, the oxynitride layer being formed by physical vapor deposition of an oxynitride of aluminum and optionally other metals from the group consisting of chromium, hafnium, zirconium, yttrium, silicon and combinations thereof;
• depositing a nitride layer over the oxynitride layer to form an alternating layer, the nitride layer being formed by physical vapor deposition of a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof, and
• optionally repeating the steps of depositing the oxynitride layer and the nitride layer;
• characterized in that nitrogen is supplied continuously and in a controlled manner during the vapor deposition of the base layer, the oxynitride layer and the nitride layer, and
• wherein an intermediate layer is applied by physical vapor deposition both between the base layer and the at least one alternating layer adjoining it and also after the application of the oxynitride layer and optionally after the application of the nitride layer, wherein the intermediate layer consists of an oxynitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof.

Further features and advantages of the present invention result from the following description of a preferred embodiment. However, the following examples serve only to illustrate the invention and are not to be construed in a limiting sense.

Production example 1

In an Innova™ PVD coating system from Oerlikon-Balzers, a substrate for a cutting tool made of tungsten carbide hard metal with about 10% by weight Co was coated by arc evaporation with a base layer of AlTiN and a top layer of three successive alternating layers, each with an oxynitride layer made of AlO _x N _1-x and a nitride layer made of AlTiN.

An intermediate layer of AlTiO _x N _1-x with an oxygen gradient was deposited between the base layer and the oxynitride layer of the first alternating layer, between the oxynitride layer and the nitride layer of each alternating layer and between the adjacent alternating layers.

A cathode with a composition Al67Ti33 (atomic %) was used to deposit the titanium-containing layers. The nitrogen partial pressure was controlled in a range of 3.0 to 3.5 Pa throughout the duration of the coating. Oxygen was supplied at a flow rate of 30 to 50 sscm during the deposition of the oxynitride layers and the intermediate layers.

The AlTiN base layer had a thickness of 3.7 µm. The total thickness of the top layer was 1.9 μm, resulting in a total coating thickness of 5.6 μm.

Further parameters of the coating deposited on the substrate are given in Table 1 below: Table 1: PVD coating structure layer composition cathodes base layer AlTiN AlTi top layer liner AlTiO _x N _1-x AlTi / Al oxynitride layer AlO _x N _1-x Al liner AlTiO _x N _1-x AlTi / Al nitride layer AlTiN AlTi liner AlTiO _x N _1-x AlTi / Al oxynitride layer AlO _x N _1-x Al liner AlTiO _x N _1-x AlTi / Al nitride layer AlTiN AlTi liner AlTiO _x N _1-x AlTi / Al oxynitride layer AlO _x N _1-x Al liner AlTiO _x N _1-x AlTi / Al nitride layer AlTiN AlTi

Production example 2

A substrate for a cutting _tool made of _tungsten carbide cemented carbide with about 10 wt _-x and a nitride layer made of AlTiN.

An intermediate layer of (Al,Cr)TiO _x N _1-x with an oxygen gradient was deposited between the base layer and the oxynitride layer of the alternating layer and between the oxynitride layer and the nitride layer in the alternating layer.

The respective layers were deposited in accordance with the parameters given in Preparation Example 1. For the deposition of the oxynitride layer and the intermediate layer, instead of the aluminum nium cathode used a cathode with a composition AI70Cr30 (atomic %). The base layer and the nitride layer were each deposited using an AlTi cathode.

The AlTiN base layer had a thickness of 3.6 µm. The total thickness of the top layer was 0.8 μm, resulting in a total coating thickness of 4.4 μm.

Production example 3

A hard metal substrate for a cutting tool made of 85.5% by weight of tungsten carbide, 2.5% by weight of mixed carbides and 12% by weight of Co with a base layer of AlTiN and a top layer of three successive alternating layers, each with an oxynitride layer made of AlO _x N _1-x and a nitride layer made of AlTiN.

An intermediate layer of AlTiO _x N _1-x with an oxygen gradient was deposited between the base layer and the oxynitride layer of the first alternating layer, between the oxynitride layer and the nitride layer of each alternating layer and between the adjacent alternating layers. The other coating parameters corresponded to those of production example 1.

The AlTiN base layer had a thickness of 3.5 µm. The total thickness of the top layer was 1.8 μm, resulting in a total coating thickness of 5.3 μm.

Production example 4

A hard metal substrate for a cutting tool made of 81.5% by weight of tungsten carbide, 10.5% by weight of cubic mixed carbides and 8% by weight of Co was coated in a PVD coating system with a base layer of AlTiN and a top layer of three successive alternating layers with each provided with an oxynitride layer made of (Al,Cr)O _x N _1-x and a nitride layer made of AlTiN.

An intermediate layer of (Al,Cr)TiO _x N _1-x with an oxygen gradient was deposited between the base layer and the oxynitride layer of the alternating layer and between the oxynitride layer and the nitride layer in the alternating layer.

The respective layers were deposited in accordance with the parameters given in Preparation Example 1. To deposit the oxynitride layers and the intermediate layers, a cathode with a composition Al85Cr15 (atomic %) was used instead of the aluminum cathode.

The AlTiN base layer had a thickness of 3.1 µm. The total thickness of the top layer was 1.8 μm, resulting in a total coating thickness of 4.9 μm.

Comparative example 1

For comparison, the hard metal substrates of production examples 1 to 4 were provided with an AlTiN coating by arc evaporation in an Innova™ type PVD coating system from Oerlikon-Balzers. The Al:Ti atomic ratio was about 67:33. The AlTiN coating ranged in thickness from about 3.3 to 4.1 µm.

Comparative example 2

In a PVD coating system, a hard metal substrate for a cutting tool made of 85.5% by weight of tungsten carbide, 2.5% by weight of mixed carbides and 12% by weight of Co with a base layer of AlTiN and a top layer of a single alternating layer with a Oxinitride layer made of (Al,Cr) ₂ O ₃ and a nitride layer made of AlTiN. A cathode with an Al:Cr atomic ratio of 70:30 was used to deposit the oxynitride layer.

The AlTiN base layer had a thickness of 2.8 µm. The total thickness of the top layer was 2.0 μm, resulting in a total coating thickness of 4.8 μm

Cutting test 1

Cutting tools according to production example 1 with a cutting plate geometry HNGJ0905ANSN-GD were used in milling tests with a 6-tooth face milling cutter on a workpiece made of steel of grade 1.4301 and compared with corresponding cutting tools which were coated according to comparative example 1.

In the single-tooth test, the milling cutter was operated at a cutting speed vc of 120 m/min, a cutting depth ap of 1 mm and an engagement width of 55 mm. The tooth advance was 0.25 mm. Milling was done dry, without cooling.

The end of the tool life was defined by flank wear > 0.2 mm or fracture of the cutting edge.

A service life of 7.5 m milling length could be achieved with the cutting tools coated according to the invention. The service life of the cutting tools coated according to Comparative Example 1 was only 4.5 m.

cutting test 2

Cutting tools according to production example 2 with a cutting plate geometry HNGJ0905ANSN-GD were used in milling tests with a 6-tooth face milling cutter on a workpiece made of steel of grade 1.4301 and compared with corresponding cutting tools which were coated according to comparative example 1.

In the single-tooth test, the milling cutter was operated at a cutting speed vc of 100 m/min, a cutting depth ap of 1 mm and an engagement width of 50 mm. The tooth advance was 0.25 mm. Milling was done with emulsion cooling.

The end of the tool life was defined by flank wear > 0.2 mm or fracture of the cutting edge.

A service life of 2.4 m milling length could be achieved with the cutting tools coated according to the invention. The service life of the cutting tools coated according to Comparative Example 1 was only 1.8 m.

cutting test 3

Cutting tools according to production example 3 with a cutting plate geometry XPHT160412 were used in milling tests with a 6-tooth shoulder milling cutter on a workpiece made of steel of grade 1.4301 and compared with corresponding cutting tools according to comparative examples 1 and 2.

In the single-tooth test, the milling cutter was operated at a cutting speed vc of 250 m/min, a cutting depth ap of 2.5 mm and an engagement width of 24 mm. The tooth advance was 0.15 mm. Milling was done without cooling.

The end of the tool life was defined by flank wear > 0.3 mm or fracture of the cutting edge.

A service life of 2.1 m milling length could be achieved with the cutting tools coated according to the invention. The service life of the cutting tools coated according to Comparative Examples 1 and 2 was only 1.2 m in each case.

Cutting test 4

Cutting tools according to production example 4 with a cutting plate geometry XPHT160412 were used in milling tests with a 6-tooth shoulder milling cutter on a workpiece made of nodular graphite of the EN-GJS-700 type and compared with corresponding cutting tools according to comparative example 1.

In the single-tooth test, the milling cutter was operated at a cutting speed vc of 250 m/min, a cutting depth ap of 1 mm and an engagement width of 20 mm. The tooth advance was 0.25 mm. Milling was done without cooling.

The end of the tool life was defined by flank wear > 0.1 mm or fracture of the cutting edge.

A service life of 12.8 m milling length could be achieved with the cutting tools coated according to the invention. The service life of the cutting tools coated according to Comparative Example 1 was only 9.0 m.

The coating according to the invention thus makes it possible to increase the service life of cutting tools by more than 30%, in some cases significantly more than 70%.

Claims (26)

A coated body having a substrate and a wear resistant coating applied to the substrate by physical vapor deposition, the coating comprising: a base layer applied to the substrate to a thickness of 1 to 10 µm, the base layer being formed from a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof; and a cover layer adjoining the base layer with a thickness of 0.1 to 5 µm, the cover layer comprising repeating alternating layers of an oxynitride layer and a nitride layer arranged over the oxynitride layer, wherein the oxynitride layer is an oxynitride of aluminum and optionally other metals from the group consisting of chromium, hafnium, zirconium, yttrium, silicon and combinations thereof and the nitride layer is a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si , Zr and combinations thereof is formed, wherein in the repeating alternating layers between the oxynitride layer and the nitride layer and optionally between successive alternating layers there is an intermediate layer formed from an oxynitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof is and wherein the oxynitride layer has a nitrogen content of less than 50 atomic percent based on the content of nitrogen and oxygen in the oxynitride layer. Coated body after claim 1 , characterized in that the base layer of the coating consists of aluminum titanium nitride and/or aluminum titanium silicon nitride, preferably aluminum titanium nitride. Coated body after claim 1 or 2 , characterized in that the base layer has an Al:Ti atomic ratio in a range from 60:40 to 70:30, preferably from 62:38 to 65:35. Coated body according to one of Claims 1 until 3 , characterized in that the top layer adjoining the base layer in the coating has 1 to 10 repetitions, preferably 3 to 5 repetitions, which has at least one alternating layer of oxynitride layer and nitride layer Coated body according to one of Claims 1 until 4 , characterized in that the thickness of an alternating layer of oxynitride layer and nitride layer is in a range from 0.1 µm to 1 µm. Coated body according to one of Claims 1 until 5 , characterized in that the oxynitride layer in the at least one alternating layer consists of an oxynitride of aluminum, preferably AlO _x N _1-x with 0.5 < x ≤ 0.99, or an oxynitride of aluminum and chromium, preferably (Al, Cr) O _x N _1-x with 0.5 < x ≤ 0.99. Coated body according to one of Claims 1 until 6 , characterized in that the oxynitride layer contains 1 to 30 atom % nitrogen, preferably 2 to 15 atom % nitrogen. Coated body according to one of Claims 1 until 7 , characterized in that the intermediate layer consists of an oxynitride of aluminum and titanium, preferably of (Al,Ti)O _x N _1-x 0 <x <1. Coated body according to one of Claims 1 until 8th , characterized in that the intermediate layer is also arranged between the base layer and the at least one alternating layer adjoining it. Coated body according to one of Claims 1 until 9 , characterized in that the intermediate layer has an oxygen gradient, the proportion of oxygen in the intermediate layer increasing in the direction of the oxynitride layer and/or decreasing in the direction of the nitride layer. Coated body according to one of Claims 1 until 10 , characterized in that the intermediate layer is formed from (Al,Cr)O _x N _1-x with 0<x<1. Coated body according to one of Claims 1 until 11 , characterized in that the coating has an outermost layer of TiN, ZrN, CrN and/or AlCrN lying over the cover layer. A coated body having a substrate and a wear resistant coating applied to the substrate by physical vapor deposition, the coating comprising: a base layer applied to the substrate to a thickness of 1 to 10 µm, the base layer being formed from a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof; and a cover layer adjoining the base layer with a thickness of 0.1 to 5 µm, the cover layer comprising at least one alternating layer made of an oxynitride layer and a nitride layer arranged over the oxynitride layer, wherein the oxynitride layer is an oxynitride of aluminum and optionally other metals from the group consisting of chromium, hafnium, zirconium, yttrium, silicon and combinations thereof and the nitride layer is a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si , Zr and combinations thereof is formed, wherein the oxynitride layer has a nitrogen content of less than 50 atomic percent, based on the proportion of nitrogen and oxygen in the oxynitride layer, an intermediate layer consisting of an oxynitride of aluminum and at least one other metal from the Ti, Cr, Si, Zr and combinations thereof existing group is formed. Process for the production of a wear-resistant coated body according to one of Claims 1 until 12 comprising the steps of: providing a substrate; applying a base layer to the substrate to a thickness of 1 to 10 µm, the base layer being formed by physical vapor deposition of a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof; depositing at least one oxynitride layer over the base layer, the oxynitride layer being formed by physical vapor deposition of an oxynitride of aluminum and optionally other metals from the group consisting of chromium, hafnium, zirconium, yttrium, silicon and combinations thereof; depositing a nitride layer over the oxynitride layer to form an alternating layer, the nitride layer being formed by physical vapor deposition of a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof, and repeating the steps of depositing the oxynitride layer and the nitride layer; characterized in that nitrogen is supplied continuously and in a controlled manner during the vapor deposition of the base layer, the oxynitride layer and the nitride layer, with an intermediate layer being applied by physical vapor deposition after the application of the oxynitride layer and optionally after the application of the nitride layer, the intermediate layer consisting of an oxynitride aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr, and combinations thereof. procedure after Claim 14 , characterized in that a nitrogen partial pressure during the application of the base layer and/or the nitride layer is in a range from 1 to 8 Pa, preferably from 2 to 5. procedure after claim 15 , characterized in that a mixed Al/Ti cathode, optionally doped with Cr, Si and/or Zr, is used as the cathode for the physical vapor deposition. procedure after Claim 14 or 15 , characterized in that for applying the oxynitride layer, oxygen is supplied in an amount of 10 to 100 sccm, preferably in an amount of 40 to 60 sccm. Procedure according to one of Claims 14 until 17 , characterized in that a nitrogen partial pressure is maintained in a range from 1 to 8 Pa, preferably from 2 to 5 Pa, during the application of the oxynitride layer. Procedure according to one of Claims 14 until 18 , characterized in that a nitrogen partial pressure is kept lower during the vapor deposition of the oxynitride layer than during the application of the nitride layer. Procedure according to one of Claims 14 until 19 , characterized in that an aluminum cathode, optionally doped with chromium, hafnium, zirconium, yttrium and/or silicon, is used as the cathode for the physical vapor deposition of the oxynitride layer. Procedure according to one of Claims 14 until 20 , characterized in that oxygen is supplied with increasing or decreasing volume flow during the application of the intermediate layer. Procedure according to one of Claims 14 until 21 , characterized in that the volume flow of oxygen varies in a range from 50% to 100% of a volume flow of oxygen supplied when the oxynitride layer is applied. Procedure according to one of Claims 14 until 22 , characterized in that a nitrogen partial pressure is maintained in a range from 1 to 8 Pa, preferably from 2 to 5 Pa, during the application of the intermediate layer. Procedure according to one of Claims 14 until 23 , characterized in that the nitrogen partial pressure during the application of the intermediate layer is lower than when applying a nitride layer. Procedure according to one of Claims 14 until 24 , characterized in that an intermediate layer is further applied by physical vapor deposition between the base layer and the alternating layer adjacent thereto, the intermediate layer being composed of an oxynitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof is formed. Method for producing a wear-resistant coated body according to Claim 13 comprising the steps of: providing a substrate; applying a base layer to the substrate to a thickness of 1 to 10 µm, the base layer being formed by physical vapor deposition of a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof; depositing at least one oxynitride layer over the base layer, the oxynitride layer being formed by physical vapor deposition of an oxynitride of aluminum and optionally other metals from the group consisting of chromium, hafnium, zirconium, yttrium, silicon and combinations thereof; depositing a nitride layer over the oxynitride layer to form an alternating layer, the nitride layer being formed by physical vapor deposition of a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof, and optionally repeating the steps depositing the oxynitride layer and the nitride layer; characterized in that nitrogen is supplied continuously and in a controlled manner during the vapor deposition of the base layer, the oxynitride layer and the nitride layer, and both between the base layer and the at least one alternating layer adjoining it and after the application of the oxynitride layer and optionally after the application of the nitride layer in each case an intermediate layer is applied by physical vapor deposition, wherein the intermediate layer consists of a oxynitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr, and combinations thereof.